Platinum and palladium complexes

ABSTRACT

A method of preparing bis(cis,cis-cyclo-octa-1,5 diene) platinum and palladium by reducing [Pt Cl 2  (1,5-C 8  H 12 )] or [Pd Cl 2  (1,5-C 8  H 12 )] in the presence of a solvent not having an active hydrogen atom, methods of preparing various other platinum and palladium compounds, some of which are novel from bis(cis,cis-cyclo-octa-1,5 diene) platinum and palladium, and methods of depositing films of platinum or palladium metal on a substrate by coating the substrate with various platinum or palladium compounds which are then decomposed.

This invention relates to a novel method of preparing bis (cis,cis-cyclo-octa-1,5 diene) platinum and palladium, to several new classesof platinum and palladium compounds which can conveniently be preparedfrom them or otherwise and which have possible applications inhomogeneous catalysis, and to new methods of making certain knownplatinum and palladium compounds from them. The invention furtherrelates to novel methods of depositing a thin film of metallic platinumor palladium on a substrate, to form a catalyst useful in heterogeneouscatalysis.

According to one aspect of the invention we provide a method ofpreparing bis (cis,cis-cyclo-octa-1,5 diene) platinum or palladium inwhich a reducing agent is allowed to react with [PtCl₂ (1,5 - C₈ H₁₂)]or [PdCl₂ (1,5-C₈ H₁₂)] and excess cis, cis-cyclo-octa-1,5 diene in thepresence of a solvent not having an active hydrogen atom.

One preferred reducing agent is the lithium derivative ofcyclo-octa-1,3,5,7-tetraene (Li₂ C₈ H₈), in which case diethyl ether isa preferred solvent. Examples of other possible reducing agents arealkali metal naphthalides, lithium metal in pyridine as solvent, andNaH₂ Al (OCH₂ CH₂ OMe)₂.

Bis (cis,cis-cyclo-octa-1,5 diene) platinum and palladium are convenientstarting materials for the preparation of other platinum and palladiumcompounds.

Novel platinum and palladium compounds which we have prepared from thesematerials and which are within the scope of this invention are those ofthe general formulae:

    R.sub.3 P-- Pt--PR.sub.3

    pt(Q).sub.3

    pt.sub.3 (R.sup.1 NC).sub.6

    pd(Q).sub.3

    pt(Q).sub.2 ER.sub.3.sup.2

    pd(Q).sub.2 ER.sub.3.sup.2

wherein R₃ P-- is a bulky trisubstituted phosphine group, for example,tricyclohexyl phosphine, R¹ is an alkyl or aryl group, Q is a compoundwhich contains at least one olefinic or acetylenic double or triplebond, such as an olefin, allene, acetylene, or substituted olefin, E isP, As, Sb or N and R² is aryl, alkyl, or alkoxyl. A mixed complexcontaining those mentioned above can also be prepared.

Novel compounds of the general formula R₃ P--Pt--PR₃, and knowncompounds of the formula R₃ P--Pd--PR₃, can be prepared by treatingPt(C₈ H₁₂)₂ or Pd(C₈ H₁₂)₂, respectively with appropriately substitutedbulky phosphine; the phosphine must be bulky so that not more than twoof the molecules can form a bond with the Pt atom. The product containsa 14-electron two-coordinate platinum (0) species. R₃ P--Pt--PR₃ can beconverted e.g. with H₂ to give the known four coordinate platinumcomplex - ##STR1## Treatment of Pt(C₈ H₁₂)₂ with the appropriateisonitrile (R¹ NC) in a solvent such as petroleum ether affords a novelcompound of the formula Pt₃ (R¹ NC)₆. This can be converted to aheterocyclic platinum complex by reaction with an electronegativelysubstituted unsaturated compound e.g. treatment with hexafluoro acetone(CF₃)₂ C═O yields the known complex: ##STR2##

The cyclooctadiene molecules in PT(C₈ H₁₂)₂ and Pd (C₈ H₁₂)₂ can also bereplaced by other ethylenically-unsaturated ligands, oracetylenically-unsaturated ligands, e.g. ethylene, butadiene oracetylene, to form the complexes Pt(Q)₃ or Pd(Q)₃ mentioned above, byreacting them with the appropriate unsaturated compound in a suitablyinert solvent e.g. petroleum ether.

These complexes Pt(Q)₃ and Pd(Q)₃ may also be prepared by reacting[PtCl₂ (1,5-C₈ H₁₂)] or [PdCl₂ (1,5-C₈ H₁₂)] with a reducing agent (e.g.Li₂ C₈ H₈) and the appropriate olefinically or ethylenically unsaturatedcompound Q. Examples of such compounds which are suitable arebicyclo(2.2.1)heptene.

We further provide novel Pt or Pd complexes of the formulae Pd(Q)₂ ER₃ ²and Pt(Q)₂ ER₃ ² in the preparation of which ER₃ ² is allowed to reactin an inert solvent with Pd(Q)₃ or Pt(Q)₃.

The complexes Pt(Q)₃ and Pd(Q)₃ are easily decomposed by heating andthus afford a relatively simple way of depositing a layer of pureplatinum or palladium metal on a substrate. For example, trisethyleneplatinum decomposes to deposit pure platinum, the only other productbeing C₂ H₄ which comes off as gas, leaving no impurities in theplatinum layer. A convenient way of applying trisethylene platinum to asubstrate is in solution form, although as trisethylene platinum isslightly volatile, and as its vapour is stable in a binary mixture withethylene gas, it may also be deposited from the vapour. A mixture ofethylene and trisethylene platinum is passed over the substrate untilthe substrate has become coated with the trisethylene platinum. This isthen decomposed e.g. either by gentle heating or by passing over thesubstrate a gas other than ethylene. A platinum layer can also bedeposited on a substrate by coating the substrate withcis,cis-cyclo-octa-1,5-diene platinum e.g. in solution form anddecomposing it. Our researches indicate that platinum and palladiumlayers thus deposited have potentially valuable catalytic properties.Thus according to a further feature of the invention we provide a methodof forming a catalytically active layer of Pt or Pd metal on a substrateby coating the substrate either with cis,cis-cyclo-octa-1,5-dieneplatinum or with a complex Pt(Q)₃ or Pd(Q)₃ in which Q is a compoundcontaining at least one ethylenically or acetylenically unsaturatedgroup, and then heating the coated substrate to decompose the complex.

We also provide a catalyst prepared by any of these methods.

The catalysts have potential applications in heterogeneous catalysis. Inaddition, all of the above novel Pt and Pd compounds have potentialapplications in homogeneous catalysis, e.g. in hydrosilation or totrimerise butadiene.

The deposition of Pt or Pd surfaces as described above, especially fromthe vapour phase, is potentially useful in the manufacture ofsemiconductors and other electrical devices.

Some specific and more detailed non-limiting examples of the inventionwill now be given.

All of the crystallographic data in this specification was obtained bysingle crystal x-ray Crystallography, carried out by Dr. Judith A.Howard at the University of Bristol, England.

EXAMPLE 1 Preparation of cis,cis-cyclo-octa-1,5-diene platinum

A sample of the compound [PtCl₂ (1,5-C₈ H₁₂)] (3.7 g, 10 mmol) wasfinely powdered and suspended in freshly distilledcis,cis-cyclo-octa-1,5-diene (15 cm³). The mixture was degassed andcooled to -40° C and a solution of the lithium derivative ofcyclooctatetraene (Li₂ C₈ H₈) (10 mmol) in diethyl ether was added over5 minutes. The resulting slurry was allowed to warm to -10° C (1 hr.)and the solvent was evaporated at reduced pressure. Extraction of theresidue with dry toluene (5 × 60 cm³ portions) at 0° gave a brownsolution which was filtered through a short column (12 cm) of alumina.The volume of solvent was reduced in vacuo to Ca. 20 cm³ and the motherliquor decanted from the white crystalline product,cis,cis-cycloocta-1,5-diene platinum, (yield 50%).

The Li₂ C₈ H₈ was prepared by suspending lithium foil (1 g.) in drydiethyl ether (80 cm³), cyclo octa-tetraene (3 cm³) was added and themixture stirred for 16 hr. The resulting solution was standardized byhydrolysis of a known volume and titration with standard aqueoushydrochloric acid. ¹ H n.m.r. spectrometry on Pt(C₈ H₁₂)₂ showedresonances (C₆ H₆) at 5.80 (J_(HPt) 55H_(Z)) and 7.81.

EXAMPLE 2 Preparation of Pt₃ (Bu^(t) NC).sub. 6

Pt(1,5-C₈ H₁₂)₂ was treated with excess Bu^(t) NC in petroleum ether andorange-red crystals of [Pt₃ (Bu^(t) NC)₆ ] were formed, (infra red bands(Nujol) were found at 2150vs, 2095sh, 1730sh and 1710vs CM⁻¹). Analogouscomplexes have also been prepared in a similar manner in which thetertiary butyl groups are replaced by methyl and cyclohexyl groups. Thestructure of [Pt₃ (Bu^(t) NC)₆ ] was determined by single crystal x-raycrystallography.

Crystal Data: monoclinic, P2_(1/n) , Z = 4 in a unit cell of dimensionsa = 18.213(7), b = 11.811(7), c = 21.966(6) A; β = 110.21(3)°; R = 0.061for 3680 reflections.

The molecular structure is illustrated in FIG. 1 from which the H atomshave been omitted from the tertiary butyl groups for clarity. Thiscomplex crystallises with the inclusion of four molecules of toluene perunit cell: these too have been omitted from the drawing.

The structure consists of an approximately equilateral triangle, meanPt--Pt distance 2.632 A, with threee briding and three terminaltertiary-butylisonitrile ligands. The terminal groups form an almostlinear Pt--C₁ --N--C₂ chain (mean C₁ 176°, mean N 170°), whereas thebridging groups show considerable bending (mean CNC 143°). The bridgingcarbon atoms lie almost in the plane of the Pt₃ triangle, and each aresymmetrically related to two Pt atoms, with the errors given, (meanPt--C bridge distance 2.10 (3) A, Pt--C--Pt 77°). The nitrogen anddistal carbon atoms of these isonitriles show a greater deviation fromthe plane. The triangular Pt--Pt distance in [Pt₃ (Bu^(t) NC)₆ ]compares favourably with the average value of 2.65 A found in thephosphine substituted complexes [Pt₃ L₃ (μ₂ -CO)₃ ](L = phosphine).

Formation in this reaction of a stable Pt₃ species is in contrast withthe ill defined nature of the related palladium species Pd (^(t) BuNC)₂.The cluster of three Pt atoms in this complex in a sense constitutes aPt surface which suggests that this complex may have valuable catalyticproperties. However, it is interesting that the Pt₃ array is easilybroken in oxidative-addition reaction, for example treatment withhexafluoracetone affords: ##STR3##

EXAMPLE 3 Preparation of Pt(Q)₃ and Pd(Q)₃ compounds i.e. trisethyleneplatinum, trisethylene palladium, tetrafluoroethylene bisethyleneplatinum, tris(bicyclo(2.2.1) heptene) platinum and palladium

Ethylene (at 1 atmosphere, 18° C) displaces the cyclo-octa-1,5,-dienefrom Pt(C₈ H₁₂)₂ in petroleum ether solution to givetrisethyleneplatinum as a white crystalline solid (on cooling). This isunstable in solution except under an ethylene atmosphere. Thepreparation of the corresponding Pd compound is analagous but in thiscase it is important to ensure that the reaction temperature does notrise above -20° C. ¹ H n.m.r. spectroscopy of the Pt compound (C₆ H₆,30° C) shows resonance at 6.83 (J_(PtH) 57.0 Hz); ¹⁹⁵ Pt resonance(INDOR) + 1609 p.p.m. (w.r.t. 21.4 MHz) shows the central 9 lines withthe correct relative intensity of the expected 13 line multiplet. Incontrast, the recently reported complex [Ni(C₂ H₄)₃ ] is apparently lessstable than the platinum analogue and shows a ¹ H n.m.r. signal (-30° C)at 6.89, which is shifted downfield in the presence of C₂ H₄. It issuggested that trisethylene-platinum has the trigonal-planar structureillustrated in FIG. 2 rather than a structure in which the C:C doublebonds are perpendicular to the coordination plane. This assumption whichis based on the structure established by x-ray crystallography for tris[bicyclo(2.2.1 )heptene] nickel, receives support from a theoreticalstudy of the complexes Ni(C₂ H₄)_(n) (n = 2,3 or 4).

Since the structural study of the Pt(C₂ H₄)₃ presented some difficultiesone of the ethylenes was displaced with tetrafluoroethylene in petroleumether solution to give the more stable species tetrafluoroethylene-bis(ethylene)platinum ¹ H n.m.r. (CF₃ F₆ H₅, - 25°) resonance at 6.60 (swith ¹⁹⁵ Pt satellites, J_(PtH) 45 Hz), ¹⁹ F resonance C₆ D₆ /toluene -30°; rel. CCl₃ F) at 123.6 p.p.m. (s with ¹⁹⁵ Pt satellites, J_(PtF) 248Hz.), ¹³ C n.m.r. resonances C₆ D₆ /toluene; rel. Me₄ Si) at -65.9p.p.m. (¹³ CH₂ ═ CH₂ , ¹ H decoupled, J_(PtC) 284 Hz) and -100.8 p.p.m.(¹³ CF₂ ═ CF₂, ¹⁹ F decoupled, J_(PtC) 470 Hz); at -80° C the ¹³ Cspectrum was unchanged.

Crystal data: monclinic, A2/a, Z = 4 in a unit cell of dimensions a =8.884(4), b = 7.552(2), c = 12.934(6) A; β = 109.51(3)°; R = 0.085 for765 reflections (Syntex P2₁ four circle diffractometer.

The three olefinic double bonds (see FIG. 3) lie in the coordinationplane of the platinum atom with Pt--C distances for Pt--C(F)₂ andPt--C(H₂) at 1.97(3) A and 2.25(3) A, respectively. Although within 2e.s.d.'s of each other at the current stage of refinement the C═C bondlengths reflect the variation in Pt--C distances, being 1.44(4) A in thecoordinated C₂ F₄ and 1.36(4) in the C₂ H₄.

In order to confirm the molecular geometry of species Pt(Q)₃ and Pd(Q)₃complex tris(bicyclo (2.2.1.) heptene) platinum (white crystals m.p.144°-145° dec., ¹ H n.m.r. resonances (C₆ D₆) at 6.64 (s with ¹⁹⁵ Ptsatellites, CH═CH, J_(PtH) 64 Hz.), 7.04 (s, CH), 8.44 (complex m,CH₂.CH₂ and 9.76 (AB system, bridging CH₂); ¹³ C n.m.r. resonances (C₆D₆) at -28.6 p.p.m. (H--C, J_(PtC) 44Hz.), -39.5 (bridging CH₂ , J_(PtC)49 Hz.) 042.8 (CH₂ .CH₂, J_(PtC) 14 Hz.) and -68.0 (CH═CH, J_(PtC) 189Hz.) was synthesized by treating bis(cyclocta-1,5-diene)platinum withbicyclo (2.2.1.)heptene, or more directly by reaction of (PtCl₂ (1,5-C₈H₁₂) with Li₂ C₈ H₈ in Et₂ O in the presence of excess bicyclo(2.2.1.)heptene.

In the molecular structure (see FIG. 4) (Crystal data: orthorhombic, P2₁2₁ 2₁, Z = 4 in a unit cell of dimensions a = 5.720(1), b = 10.740(4), c= 28.771(12) A; R = 0.106 for 1695 reflections) the double bonds of thethree bicyclo(2.2.1) heptene ligands lie in the coordination plane ofthe platinum atom, at a mean Pt--C distance of 2.22(3)A. The maximumdeviation from this plane is currently 0.06 A. The bridgehead carbonatoms C(7) and C(21) lie 2.3 A to one side of this plane, and the thirdbridgehead carbon C(14) is 2.3 A on the opposite side, all lyingapproximately 3.2 A from the platinum atom. The C═C bonds have a meanbond length of 1.38(4) A, which is essentially the same as found forcoordinated ethylene. The remaining C--C bond lengths in the coordinatedbicyclo (2.2.1)heptene ligands are those expected for singly bondedcarbon atoms. The average dihedral angle at the bend of the C₇ rings,i.e. between planes C(1)C(2) C(3)C(6) and C(3)C(6)C(5)C(4) etc. is 105°.

A finely powdered sample (1.14g, 4 mmol) of [PdCl₂ (1,5-C₈ H₁₂)₂ ] indry diethyl ether was treated with excess bicyclo(2.2.1)heptene. Themixture was de-gassed and cooled to -40° C and a solution of Li₂ C₈ H₈(4 mmol) in diethl ether was added over 5 minutes. The resultant slurrywas warmed to about -10° C and solvent removed at reduced pressure.Extraction of the residue with dry petroleum (10° C) gave a palesolution from which white needles of tris (bicyclo(2.2.1)heptene)palladium (yield 60%) were obtained by cooling to -20° C. Insolution this decomposes to palladium metal unless an excess of ligandis present. Crystals of this compound have the same morphology as theanalogous platinum compounds, and x-ray photographs indicate they arenot only isomorphous but also isostructural. Cell constants are almostidentical and the space group is also P2₁ 2₁ 2₁ with four molecules perunit cell (a = 5.705(1), b = 10.784(5) and c = 28.770(15)A).

Thus in both of the 3-coordinate species eterafluoroethylenebis(ethylene) platinum and tris(bicyclo (2.2.1)heptene) platinum wherePt(O) is stabilised by olefinic ligands with different steric andelectronic requirements, and also in the case of the Pd(O) complextris(bicyclo (2.2.1)heptene) palladium, a trigonal planar structure ispreferred.

EXAMPLE 4 Preparation of CyP₃ --Pt--PCy₃

Reaction of Pt(C₈ H₁₂)₂ with tri-cyclohexylphosphine afforded a14-electron two coordinate platinum (O) species CyP₃ --Pt--PCy₃, anobservation which is of interest in view of recent studies which haveestablished the structural indentity of the analogous palladium species.This complex, which dissolves in toluene to give an orange-yellowsolution, reacts (on bubbling) with molecular hydrogen to form a stabledihydride ##STR4## i.r. (Nujol) 1710 cm⁻¹, ¹ H n.m.r. resonance (C₆ H₆)at 13.10 (t with ¹⁹⁵ Pt satellites, J_(HPt) 2872 Hz), formulated as thetrans-isomer.

The reactions described in the above Examples are shown set outschematically in FIG. 2.

EXAMPLE 5 Preparation of bis(cis,cis-cyclo-octa-1,5-diene)palladium

A sample of the compound [PdCl₁ (1,5-C₈ H₁₂)] (2.85g. 10 mmol) wasfinely powdered and suspended in freshly distilledcis,cis-cyclo-octa-1,5-diene (15 cm³). The mixture was degassed andcooled to -40° C and a solution of the lithium derivative ofcyclooctatetraene (Li₂ C₈ H₈) (10 mmol) in diethyl ether was added over5 minutes. at -30° C before being filtered through a short column (3 cm)of alumina at -30° C under an atmosphere of ethylene. The filtrate wascollected in a tube cooled to -40° C. Careful removal of ethylene atreduced pressure caused the precipitation of a white material which,after decanting off the mother liquor, was washed with diethyl ether orbutane at -30° C and dried under vacuum to give purebis(cis,cis-cyclo-octa-1,5-diene)palladium. (Yield 60%).

Treatment of the product with bicyclo (2.2.1) heptene gave tris(bicyclo(2.2.1)heptene)palladium. Ethylene (1 atmos., -30°) displacescyclo-octa-1,5-diene from bis(cyclo-octa-1,5-diene)palladium, as wasobserved with the analogous Pt(1,5-C₈ H₁₂)₂, to give a highly reactivewhite crystalline complex, showing a ¹ H n.m.r. resonance (d⁸ -toluene,-60°) at T6.62(s). This complex is probably tris(ethylene)palladium,although present evidence does not exclude its formulation as (Pd(C₂H₄)₄).

EXAMPLE 6 Preparation of tricyclohexylphosphine bis(ethylene) palladiumand platinum and trimethylphosphine bisethyleneplatium

Addition of tricyclohexylphosphine to the white crystalline compoundprepared in Example 5 gave tricyclohexylphosphine-bis(ethylene)palladium¹ H n.m.r. resonance (d⁸ -toluene, -35°) at 6.79 (s, CH₂ ═CH₂).

To a solution of the white crystalline complex (2 mmol), prepared insitu from Pd(1,5-C₈ H₁₂)₂ and ethylene in petroleum ether (40 cm³) at-30° C, was added a solution of tricyclohexylphosphine (2 mmol) inpetroleum ether (10 cm³). The solution was filtered through alumina intoa tube cooled to -78° C, giving white crystals of the product,tricyclohexylbis(ethylene)palladium, which were dried in a stream ofethylene at 0° C. (Yield 70%).

Similarly, there were prepared from trisethyleneplatinum and one molarequivalent of tricyclohexylphosphine and trimethylphosphinerespectively, crystalline complexestricyclohexylphosphinebis-(ethylene)platinum [¹ H n.m.r. resonances (C₆H₆, 35°) at 7.22 (s with ¹⁹⁵ Pt satellites, CH₂ ═CH₂, J_(PtH) 58 Hz.)and 8.42 (br.m)] and trimethylphosphinebis(ethylene)platinum [¹ H n.m.r.resonances (C₆ H₆, 35°) at 7.32 (s with ¹⁹⁵ Pt satellites, CH₆ ═CH₆,J_(PtH) 57 Hz.) and 8.78 (d with ¹⁹⁵ Pt satellites, PMe₃, J_(PH) 8.5Hz., J_(PtH) 21.5 Hz.) ¹³ C n.m.r. resonances (d⁸ -toluene) (C₂ H₄resonances only, +30°) -36.7 p.p.m. (s with ¹⁹⁵ Pt satellites, J_(PtC)152 Hz.); at -40° two resonances were observed at -33.6 p.p.m. (d with¹⁹⁵ Pt satellites, J_(PC) 15.0 Hz., J_(PtC) 158 Hz.) and -38.6 p.p.m. (dwith ¹⁹⁵ Pt satellites, J_(PC) 6.0 Hz., J_(PtC) 137 Hz)].

These observation show that at room temperaturetrimethylphosphinebisethylene platinum is a fluxional molecule (aspresumably also are the two tricyclohexylphosphine complexes) where itis likely the coordinated ethylene rotates about an axis through themetal and perpendicular to the C--C bond. The low temperature ¹³ Cspectrum of trimethylphosphinebisethylene-platinum shows that the`Frozen out` structure is again a trigonal planar arrangement. It isinteresting to note that the activation energy for ethylene rotation inthis complex is clearly higher than intetrafluoroethylenebis(ethylene)platinum.

What we claim is:
 1. A method of preparing bis(cis,cis-cyclo-octa-1,5diene) platinum or palladium in which a reducing agent is reacted insolution with [PtCl₂ (1,5-C₈ H₁₂)] or [PdCl₂ (1,5-C₈ H₁₂)] and excesscis, cis,cyclo-octa-1,5-diene in the presence of a solvent not having anactive hydrogen atom.
 2. Novel platinum and palladium complexes of thegeneral formula:

    (R.sub.3.sup.2 E).sub.x (Q).sub.y M.sub.m (R.sup.1 NC).sub.z

wherein Q is a radical containing at least one olefinic double bond oracetylenic triple bond; E is P, As, Sb or N; R² is aryl, alkyl oralkoxyl; M is Pt or Pd; R¹ is an alkyl or aryl group; x is 0 or 1; y is0, 2 or 3; m is 1 or 3; z is 0 or 6; and when m is 3, then M is Pt, z is6 and both x and y are 0; and when m is 1 and z is 0, then x + y =
 3. 3.A method of preparing R₃ P--Pt--PR₃ comprising reacting in solution bis(cis, Cis-Cyclo-octa-1,5 diene) platinum with the trisubstitutedphosphine R₃ P wherein R is a bulky ligand such that not more than twoof the phosphines can form a bond with the Pt atom.
 4. A method ofpreparing ##STR5## comprising reducing in solution R₃ P--Pt--PR₃ withhydrogen wherein R is a bulky ligand such that not more than two of thephosphines R₃ P can form a bond with the Pt atom.
 5. A method ofpreparing M(Q)₃ by reacting in solution bis(cis,cis-cyclo-octa-1,5diene) M with the unsaturated compound Q in an inert solvent wherein Mis Pt or Pd and Q is a radical containing at least one olefinic doublebond or at least one acetylenic triple bond.
 6. A method of preparingPt₃ (R¹ NC)₆ by reacting in solution bis(cis, cis-cyclo-octa-1,5-diene)platinum with excess isonitrile R¹ NC in an inert solvent wherein R¹ isan alkyl or aryl group.
 7. A method of preparing R₃ E M (Q)₂ by reactingin solution M(Q)₃ with ER₃ in an inert solvent wherein M is Pt or Pd andQ is a radical containing at least one olefinic double bond or at leastone acetylenic triple bond, E is P, As, Sb or N and R is aryl, alkyl, oralkoxyl.
 8. A method of preparing Pt(Q)₃ or Pd(Q)₃ comprising reactingin solution [PtCl₂ (1,5-C₈ H₁₂)] or [PdCl₂ (1,5-C₈ H₁₂)] respectivelywith a reducing agent and the compound Q wherein Q is a radicalcontaining at least one olefinic double bond or acetylenic triple bond.9. A complex according to claim 2 wherein m is
 3. 10. The complex ofclaim 2 wherein m is 1.